The present application seeks to develop transgenic mouse models to study the role of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) in lung epithelial cell function in vivo. Correction of the cystic fibrosis defect will require precise knowledge of the effects of expression of the CFTR in specific cellular sites within the pulmonary epithelia. The consequences of overexpression, underexpression of ablation of the CFTR mRNA in various cells comprising the respiratory epithelium are presently unknown. The development of animal models in which CFTR expression is altered, either increased or decreased, in precise cell types within the respiratory epithelium, will be useful for the development of new strategies for therapy of cystic fibrosis, whether by genetic or pharmacologic approaches. We have developed lung epithelial cell-specific promoter-enhancer elements which will be utilized to alter the expression of CFTR in transgenic mice and rats. Tracheal-bronchial, bronchiolar-alveolar and non-selective transcriptional elements will be used to direct expression of human CFTR and delta508 mutant CFTR mRNA in transgenic mice or rats. The effects of expression of wild-type and delta508 CFTR on lung growth, morphogenesis, differentiation, and Cl transport will be discerned. Antisense murine and rat-CFTR will be expressed in specific cells of the respiratory epithelium to inhibit or ablate the synthesis of CFTR in transgenic animals. Human CFTR and delta508 CFTR will be studied in the transgenic animals utilizing in situ hybridization, immunocytochemistry and electrophysiology. The sites of expression of the CFTR transgenes will be compared with expression of the endogenous CFTR, CC10 and other cellular markers of epithelial cell subtypes in the respiratory tract. These models should be useful for the elucidation of the intracellular location, structure and function of CFTR in pulmonary epithelial cells in vivo and will generate new animal models for evaluating genetic and pharmacological therapy of cystic fibrosis.